Recently, a higher quality of work has been demanded in industrial robots. To meet this demand, a sensor for recognizing the shape of workpiece is further mounted on a work tool attached to a tip of the robot. This sensor recognizes differences with teaching points set before processing that may occur during processing, and modifies processing points in real time.
PTL1 and PTL2 describe a control method of a welding robot to which a laser sensor and welding torch are attached at its tip.
A conventional robot control method is described with reference to FIG. 17. FIG. 17 is a schematic view of a conventional welding robot. Conventional welding robot 401 includes welding torch 402 and laser sensor 403. Laser sensor 403 is provided ahead of welding torch 402 in a welding advancing direction to detect a shape of workpiece W. When welding workpiece W, welding robot 401 moves welding torch 402 and laser sensor 403 from teaching point A1 to teaching point B1 set before starting welding in a state an output of laser sensor 403 is turned ON. Laser sensor 403 recognizes a point where the shape of workpiece W changes (a point where a step occurs) as welding start point A2, and welding by welding torch 402 starts from welding start point A2. Laser sensor 403 recognizes a point where the shape of workpiece W changes (a point where the step disappears) as welding end point B2, and welding by welding torch 402 ends at welding end point B2.
Laser sensor 403 continues to detect the shape of workpiece W also during welding of workpiece W by welding torch 402, and modifies the welding point by welding torch 402. This enables to achieve welding that is applicable to any displacement in welding point that may occur during welding.